Process for producing briquetted and pressed granular material and use thereof

ABSTRACT

The present invention relates to a process for producing briquetted and pressed granular material and the use thereof for coloring building materials, such as concrete and asphalt, and organic media, such as paint systems, plastics and colored pastes.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 08/827,660,filed Apr. 10, 1997 U.S. Pat. No. 6,079,644.

The present invention relates to a process for producing briquetted andpressed granular material and the use thereof for coloring buildingmaterials, such as concrete and asphalt, and organic media, such aspaint systems, plastics and colored pastes.

The processing of pigment granules requires that the pigments be groundto primary particles in order to achieve the optimal color effect. Theresulting powders formed create a large amount of dust and, owing totheir finely-divided state, tend to adhere and stick in dosing plants.In the case of toxicologically harmful substances, during the processingprecautions must therefore be taken to avoid danger to humans and theenvironment owing to the dust formed. But even in the case of safe,inert substances such as, for example, iron oxide pigments, avoidance ofirritation due to dust is being increasingly demanded by the market.

The aim when handling pigments is accordingly avoidance of dust andimproved dosing as a result of good flow properties, in order to achievea color effect of even quality for use in building materials and organicmedia. This aim is more or less achieved by applying granulationprocesses to pigments. Here pelletizing and spray granulation aregenerally used. Compacting processes have hitherto been less suitable,owing to the limited dispersibility of the granular material obtainedthereby.

In principle, in the case of pigments the market demands twodiametrically opposing properties for the use of pigment granules:mechanical stability of the granular material and good dispersibility.The mechanical stability is responsible for good transport propertiesduring transport between manufacturer and user as well as for gooddosing and flow properties in the pigments in use. It is produced byhigh adhesive forces and is dependent, for example, on. the quantity ofbinder or even on the compacting pressure during forming. On the otherhand, the dispersibility is influenced by a thorough grinding prior togranulation (wet grinding and dry grinding), by the mechanical energyduring the incorporation (shear forces) and by dispersing agents, whichimmediately lower the adhesive forces in the dry granular materialduring the incorporation into a medium. The use of larger quantities ofdispersing agents in pigments is limited, however, owing to the costratio of additive to pigment. A high proportion of additive moreovercauses a corresponding decrease in the coloring strength or in thescattering power. As the variations in coloring strength are generallyless than ±5%, the use of additives is also restricted even if these areacting simultaneously as adhesion promoters and dispersing agents.Furthermore, the additives must not unfavorably alter the properties inuse of end products such as building materials, plastics and paints: forexample, the strength or the setting properties in concrete, thecompressive strength or abrasion resistance in asphalt and the strengthor the notch impact resistance in plastics and the elastic properties inelastomers (polymers).

Suitable production processes according to prior art for pigmentgranules are, for example, spray granulation (spray drying by disk ornozzle) and pelletizing (mixers, fluid-bed granulators, disks or drums).

The spray-drying granulation starts from pigment suspensions with theuse of binders. Relevant processes are described in various protectiverights; here water-soluble binders are used. Thus in DE-A 3 619 363,EP-A 0 268 645 and EP-A 0 365 046 the processes start from organicsubstances such as, for example, lignosulphonates, formaldehydecondensates, gluconic acids, sulphated polyglycol ethers, whereas inDE-A 3 918 694 and U.S. Pat. No. 5,215,583 the processes start frominorganic salts such as, for example, silicate and phosphate. Acombination of spray granulation and pelletizing has also been describedin EP-A 0 507 046. In DE-A 3 619 363 (column 3, lines 44-47) and EP-A 0268 645 (column 7, lines 18, 19) the use of a compacting process isadopted. In this process a strong coherence of the particles is achievedby application of pressure, so that a good transportability but at thesame time decreased properties of dispersibility are produced.

In EP-A 0 257 423 and DE-A 3 841 848, spray granulation usingpolyorganosiloxanes as hydrophobic, lipophilic additives is described.The spray-dryer mentioned generally leads to small particle sizes, thatis, to a high proportion of fine material. This means that a significantproportion of the material is not obtained from the dryer as immediatelyusable granular material, but is first retained as fine material in thefilter and has then to be returned to the process. The aftertreatmentcarried out to render the material hydrophobic, in the case ofspray-dried products, results in granular material which flows very wellbut is exceptionally dusty.

EP-A 0 424 896 discloses the production of fine granular material low indust, in a production operation in known intensive mixers. A low contentof waxes in combination with emulsifier and wetting agents is used hereby creating an aqueous dispersion. In the course of this water contentsof from 20% up to over 50% are generally obtained. These granularmaterials must first of all be dried and separated from oversize andundersize material.

DE-A 31 32 303 describes inorganic pigment granules which arefree-flowing and low in dust, which are mixed with binders renderedliquid by the action of heat and are granulated by a screening processwith the use of a screening aid (pressure). About 10 to 20% of thethroughput accumulates as fine material of <0.1 mm.

EP-A 0 144 940 discloses pigment granules low in dust which, startingfrom filtration sludge containing about 50% water, through the additionthereto of 0.5 to 10% of surfactants as well as mineral oil or waxesliquefying at 50 to 200° C., are mixed until lubrication point isreached. The procedure is carried out in intensive mixers, and ifnecessary the mixture is granulated and dried. Water is present in theend product in a quantity of 10 to 15%, which is disadvantageous forintroduction into plastics.

Other processes are also limited in their application. Spraygranulation, owing to the formation of droplets, requires the use offree-flowing and hence highly fluid suspensions. Consequently, for thedrying process a greater quantity of water has to be evaporated thanfrom highly pressed-out filtered pigment pastes during the frequentlyapplicable fluid-bed drying. This leads to high energy costs. In thecase of pigments previously produced by calcination, spray granulationinvolves an additional processing step with high energy costs. Moreover,in spray granulation a greater or lesser proportion of fine materialaccumulates, which has to be returned to the production unit.

Pelletizing, too, frequently exhibits disadvantages. Starting frompigment powder, it may be carried out in mixers under conditions of highturbulence, in the fluid-bed process or else by disk granulation anddrum granulation. Common to all these processes is that the requirementfor binder, in most cases water, is high, so that drying has to followas an additional processing step. Here, too, granular materials ofdiffering size are obtained, especially if insufficient binder isavailable for the quantity of powder or if the actual distribution isnot optimal. Then a certain fraction may be too large for use asgranular material, while on the other hand fractions which areexcessively small and hence dust-forming are still present. Aclassifying of the granular material formed is therefore necessary, withoversize and undersize material being returned.

Disk granulation leads to granular materials having a wide particle sizespectrum. Where this is undesirable because of the poor dispersibilityof excessively large particles, the granulation process has to bemonitored through intensive supervision by staff and the production ofgranular material has to be optimised by manual control of the quantityof grains. This is generally also followed by a classification andreturn of oversize and undersize material.

Extrusion processes from pastes lead to the formation of relativelysolid granular materials during drying; owing to their size, these donot guarantee an optimal dispersibility.

DE-A 42 14 195 describes a process for coloring asphalt using inorganicpigment granules, with oils being used as binders. It is a simplegranulation process.

In DE-A 4 336 613 and DE-A 4 336 612 inorganic pigment granules areproduced from pigments by mixing with binders, compacting, roughgrinding and granulating. The granular materials thus produced are nottransportable satisfactorily by pneumatic means; during transportation alarge quantity of dust is formed, which is undesirable.

SUMMARY OF THE INVENTION

It was accordingly the object of the present invention to provide aprocess which avoids the hitherto described disadvantages of spraygranulation, extrusion granulation or pelletizing in their applicationto inorganic pigments and which provides sufficiently stable granularmaterial which can be dosed, is low in dust and has a dispersibility asfar as possible equally good as that of the powders used hiltherto.

It has now been found that this object can be met by a multistepcombination of the processing steps mixing, compacting, separation andoptionally rounding.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a process for producing briquetted and pressedgranular material from inorganic pigments and auxiliary substances,which is characterised in that

a) one or more inorganic pigments are mixed with one or more of theauxiliary substances promoting processability,

b) this mixture is subjected to a pressing or briquetting step,

c) this pressed or briquetted product is comminuted,

d) the comminuted product is divided up into two or more fractions,

e) the fraction wherein at least 85% of the particles are larger than 80μm, preferably larger than 100 μm, or are between 80 and 2000 μm,preferably between 100 and 1000 μm, is removed and optionally rounded inan additional step and the other fraction or fractions is/aretransferred out of the process or returned.

Prior to step c) the pressed or briquetted product may be divided uppreferably into two fractions (intermediate step x), in order then tocomminute the coarse fraction, wherein at least 85% of the particles arelarger than 500 μm, preferably 600 μm, in step c), and to divide theother, fine fraction, once again into two or more fractions in step d),separate from or together with the product from step c).

Preferably only the fine fraction from intermediate step x) is dividedup into two or more fractions in step d), while the coarse fraction fromintermediate step x) is comminuted in step c) and is then transferredout of the process as product.

Intermediate step x) may be carried out preferably by pneumaticclassification or screening (mechanical separation). Preferablyscreening machines are used.

The comminuted product in d) is particularly preferably divided up intotwo fractions, with the fine fraction smaller than 80 μm beingtransferred out or returned to the process and the coarse fractionlarger than 80 μm optionally being rounded in an additional step.

The comminuted product may also preferably be divided up into threefractions in step d), with the fine fraction and the coarse fractionbeing transferred out of the process or returned to the process and themiddle fraction between 80 and 2000 μm, particularly preferably between100 and 1000 μm, most preferably between 100 and 500 μm, optionallybeing rounded in an additional step.

The granular materials preferably have a residual water content of lessthan 4 wt. %, particularly preferably less than 2 wt. %. This can beobtained if necessary by after-drying.

The rounding step under e) is preferably carried out with the dustfraction removed.

The product formed by the rounding in step e) may preferably in additionbe coated with auxiliary substances.

If a rounding step under e) is carried out, afterwards preferably acoarse fraction having particle sizes of >1500 μm can be separated andoptionally returned to the process.

The inorganic pigments used are preferably iron oxide, titanium dioxide,chromium oxide, rutile mixed phase pigments and mixtures of thesepigments with carbon black.

The inorganic pigment granules have bulk densities preferably of between0.5 and 4.0 g/cm³, particularly preferably between 0.5 and 2.0 g/cm³.The granules mixed with carbon black have bulk densities preferably offrom 0.3 to 1.5 g/cm³.

Both inorganic and organic substances may be used as auxiliarysubstances.

The auxiliary substances used are preferably water, salts selected fromamong the phosphates, carbonates, nitrates, sulphates, chlorides,silicates, aluminates and borates, formates, oxalates, citrates andtartrates; polysaccharides, cellulose derivatives such as, for example,cellulose ethers, cellulose esters, phosphonocarboxylic acids, modifiedsilanes, silicone oils, oils from biological cultivation (for example,rape oil, soy bean oil, maize oil, olive oil, coconut oil, sunfloweroil), refined petroleum oils based on paraffins and/or on naphthenes,synthetically produced oils, alkylphenols, glycols, polyethers,polyglycols, polyglycol derivatives, protein fatty acid condensationproducts, alkylbenzenesulphonates, alkylnaphthalenesulphonates,lignosulphonates, sulphated polyglycol ethers, melamine formaldehydecondensates, naphthalene formaldehyde condensates, gluconic acid,polyhydroxy compounds or aqueous solutions thereof.

In addition, during mixing preferably emulsifiers, wetting agents anddispersing agents may be added in a quantity of from 0.01 to 5 wt. %,preferably from 0.01 to 3 wt. %, referred to the weight of the pigmentused.

Suitable emulsifiers are in particular emulsifiers having HLB values of7 to 40, particularly 8 to 18, for use in building materials containingaqueous systems, such as concrete, and consisting of alkyl or acrylgroups and hydrophilic intermediate and end groups such as, for example,amides, amines, ethers, hydroxyl, carboxylate, sulphate, sulphonate,phosphate, amine salt, polyether, polyamide, polyphosphate. Thesubstances may be used, according to their HLB value, individually or incombination.

Suitable wetting agents are in particular alkylbenzenesulphonates, fattyalcohol sulphates, fatty alcohol ether sulphates, fatty alcoholethoxylate, alkylphenol ethoxylate, alkane sulphonates, olefinsulphonates.

Preferably melamine sulphonates, naphthalene sulphonates, metal soaps,polyvinyl alcohols, polyvinyl sulphates, polyacrylamides, fatty acidsulphates are used as dispersing agents.

To increase the stability or to assist in the processing of the granularmaterial it may be beneficial finally to coat the granular materialswith an additional layer. This layer can be produced by applyinginorganic salts in solution, polyols, oils or waxes or polyethers,polycarboxylates or cellulose derivatives, preferably carboxymethylcelluloses.

Preservatives may also be added to the granular materials during mixing,in a concentration of from 0.01 to 1 wt. %, referred to the weight ofthe pigment. Examples which may be mentioned are formaldehyde-releasingcompounds, phenolic compounds or isothiazolinone preparations.

Surprisingly,auxiliary substances for the pressed and briquettedgranular materials, in particular if these are intended forincorporation into aqueous building materials systems such as cementmortar or concrete, can be not only water-soluble substances but alsosubstances insoluble in water such as, for example, oils.

The auxiliary substances are added preferably in quantities of from0.001 to 10 wt. %, particularly preferably from 0.01 to 5 wt. %, mostpreferably from 0.1 to 3 wt. %, referred to pigment used.

The auxiliary substances can be added preferably compounded with otheradditives such as, for example, wetting agents, metal soaps, et cetera.

The pressing or briquetting step b) is preferably carried out by meansof a roll press or matrix press and preferably at line forces of from0.1 to 50 kN/cm, preferably 0.1 to 20 kN/cm.

In the pressing or briquetting (compacting, step b)) an important valueis the pressing force (kN) per cm of roll width (line force). Duringcompacting between rolls, a linear transfer of the pressing force isassumed, as a pressing surface cannot be defined and therefore apressure (kN/cm²) cannot be calculated.

The compaction is preferably carried out at low line forces. The lineforces applied are in general preferably within the lower range of thecommercially available equipment, between 0.1 and 50 kN/cm is preferred.The line forces are most preferably from 0.1 to 20 kN/cm. An example ofcommercially available equipment is the Pharmapaktor 200/50 from thefirm Bepex GmbH, Leingarten/Germany.

The additional separating step x) is carried out preferably usingscreening machines such as, for example, drum screens, oscillatingscreens and vibrating screens.

The comminution can be effected by means of all the conventionalcommercial comminution units, such as crushers, toothed roll crushers,rolls equipped with frictional devices and screen granulators.

The comminution step c) is carried out preferably using screengranulators or screen-type mills, wherein the material is pressedthrough a passing, screen having a mesh size of from 0.5 to 4 mm,particularly preferably from 0.5 to 2.5 mm, most preferably from 1 to 2mm (so-called crushers). As is generally known, the motion of the rotorsis circulating or oscillating, at a peripheral speed of from 0.05 m/secto 10 m/sec, preferably from 0.3 to 5 m/sec. The distance between rotorand screen or breaker plate is from 0.1 to 15 mm, preferably from 0.1 to5 mm, most preferably from 1 to 2 mm.

An example of the comminuting equipment which can be used is the FlakeCrusher from the firm Frewitt, Fribourg/Switzerland.

After the comminution, the fine material smaller than 80 μm is separatedoff. The quantity of this fine material is preferably from 10 to 50 wt.%, particularly preferably 10 to 30 wt. %. The fine material ispreferably returned to step b). The remaining fraction is free-flowing,can be dosed, is stable, low in dust and readily dispersible. A furtheroptimization can be achieved by additional rounding.

The rounding step e) is preferably carried out on a rotary disk, in arotary drum or dragee drum, drum screens or similar units or in a fluidbed or in a screening plant. Here the dust fraction can be removedpreferably by suction or, in the fluid bed, transported away with theair.

One of the advantages of the process according to the invention is thatit is possible to start from dried and if necessary ground pigmentpowders. This is in particular especially economic when the pigment isproduced by calcination. In the case of spray granulation, for example,a further slurrying and thereafter an additional drying step arenecessary. It is moreover very expensive as regards energy to evaporateoff again the water used for slurrying.

The process according to DE-A 4 336 613 or DE-A 4 336 612 leads, throughpelletizing on the rotary disk, to round particles which are howeverinhomog,eneous. They consist of a compact core and an external layer orlayers formed thereon, which can become abraded. These productsconsequently form dust, especially when transported pneumatically, andthe flow properties are not particularly good. The products obtained bythe process according to the invention do not have these disadvantages,as they consist of homogeneous compact particles of uniform density andstrength.

The granular materials produced by the process according to theinvention are used for coloring building materials such as, for example,concrete, cement mortar, plasters and asphalt, and for coloring organicmedia such as paints, plastics and pigment pastes and for producingdisperse dyes and slurries.

The granular materials produced according to the invention areparticularly suitable for incorporation into dry cement mortar mixturesand into plasters.

In the multistep process according to the invention it is important thatin the first step a sufficiently cohesive homogeneous material isproduced by adding the auxiliary substance in a mixer. The briquettingor pressing then takes place in the second step.

The invention also provides a process for coloring building materialssuch as concrete or asphalt using inorganic pigments, which ischaracterised in that inorganic briquetted or pressed granular materialsmade from inorganic pigments and auxiliary substances, which have beenproduced by the process according to the invention, are mixed with thebuilding material in a quantity of from 0.1 to 10 wt. %, preferably 1 to5 wt. %, referred to cement.

Another preferred use of the granular materials produced according tothe invention is in disperse dyes and slurries.

The invention further provides a process for coloring organic media suchas paint systems, plastics and pigment pastes using inorganic pigments,which is characterised in that inorganic briquetted or pressed granularmaterials made of inorganic pigments, which have been produced by theprocess according to the invention, are mixed with the organic medium ina quantity of from 0.1 to 10 wt. %, referred to organic medium.

The test of the dispersibility in building materials is carried out incement mortar by the following method by measurement of the coloringstrength on prisms produced from white cement:

Cement-quartz sand ratio 1:4; water-cement value 0.35; level ofpigmentation 1.2%, referred to cement; mixer used, obtained from RK ToniTechnik, Berlin, having 5 l mixing tub, structural type 1551, speed ofrotation 140 rev/min; batch: 500 g cement. After 100 s, 3 samples ofmixture (300 g) are taken and test pieces (5×10×2.5 cm) are preparedunder pressure (300 bar). Curing of the test pieces: 24 hours at 30° C.and 95% atmospheric humidity with subsequent drying for 4 hours at 60°C. Color data measurement by Dataflash 2000, Datacolor International,Cologne, 4 measuring points per stone, per pigment mixture 12 measuringpoints. The average values obtained are compared with the values of areference sample. The color difference E_(ab) and the coloring strength(reference sample=100%) were assessed (DIN 5033, DIN 6174). Thedispersibility is described as good at a difference in coloring strengthof up to 5% compared with the reference sample, and as satisfactory at adifference of up to 10%.

The dispersibility in asphalt was tested by the following method:

The pigment/granular pigment together with a road bitumen of the type B80 (commercial product from Shell AG) and aggregrates is mixed in aheatable laboratory mixer (Rego mixer) at 180° C. for 60 seconds. Testpieces are prepared from the mixture by Marshall's method (“The ShellBitumen Handbook, Shell Bitumen U.K., 1990, pages 230-232). Differencesin shade in the Marshall test pieces are assessed calorimetricallyagainst a preset comparative sample (Minolta Chromameter II, standardilluminant C, Cielab System, DIN 5033, DIN 6174) by comparison of thered values a*. Differences in the a* values of less than 0.5 units areindistinguishable visually.

The flow properties were tested by assessing the behavior on dischargefrom a funnel of 100 ml in volume and having a 6 mm opening, inaccordance with ASTM Test D 1200-88. If the material flows freely, theflow properties are described as good. If a flow of material does nottake place or does so only after tapping, the flow properties areconsidered to be inadequate.

The determination of the fine material as screen oversize is carried outon a VA screen in accordance with DIN 4188, having 80 μm mesh size on anair-jet screening machine of the type Alpine 200 LS. 20 g of the sampleto be tested is used. The fine material is removed by suction for arunning time of 5 minutes and the quantity of coarse fraction on thescreen is reweighed.

The dispersibility of plastics is determined in accordance with a testin DIN 53 775, part 7: “Testing of coloring materials in plasticizedpolyvinyl chloride (PVC-P) materials; determination of the dispersinghardness by two roll milling”:

The pigment to be tested is dispersed in PVC on a mixing roll at 160±5°C. The rolled sheet obtained is divided and one half is then exposed toincreased shear forces by rolling at room temperature. The measure ofthe dispersibility in the case of colored pigments is the colordifference ΔE in accordance with CIELAB (DIN 5033, 6174) between hot-and cold-rolled PVC sheets, and in the case of white pigments is thedifference of the standard tristimulus values Y (DIN 5033) between hot-and cold-rolled PVC sheets. A readily dispersible pigment can bedispersed even at low shear forces, whereas the increased shear forceson rolling at low temperature are required in order to disperse arelatively indispersible pigment. The rule is therefore: the smaller thecolor difference ΔE or the difference in the standard tristimulus valuesY, the better does the pigment disperse. The dispersibility is of greatimportance particularly in the case of granular materials, as theparticles of granular material to be dispersed in the plastics materialhave first of all to be divided. For granular materials a dispersibilityis sought which is as good as that of the corresponding pigment powders,so that the characteristic values ΔE or Y for powders and granularmaterial should not differ greatly.

The measurement of fine dust particles for determining the stability ofgranules is carried out in accordance with DIN 55992. The dust-formingproperties of the granules can be determined using a Heubach“Dustmeter”. The quantity of fine dust particles issuing from a rotatingdrum, through which a stream of air of a specific intensity is passed isdetermined gravimetrically by means of a glass fibre filter. By carryingout measurements after varying periods of exposure the progress of theformation of dust can be determined as a function of mechanical stress.

EXAMPLES

The present invention is explained in more detail below by means ofExamples, but should not be regarded as limited thereby.

Example 1 (Comparison)

50 kg of iron oxide red Bayferrox 130 (commercial product of Bayer AG)was mixed with 1% of lignosulphonate and 1% of machine oil V 100 in amixer for 10 minutes. The mixture was pressed on a compactor 200/50(firm Bepex, Leingarten) at ca. 10 kN (2 kN/cm) and then comminuted on acrusher (firm Frewitt, Fribourg, Switzerland) by means of a screen of1.5 mm mesh size. The proportion larger than 80 μm was ca. 95%. Thedispersibility in concrete, compared with the starting powder, was 100%.The bulk density was 1.07 g/cm³. The material forms a large amount ofdust and does not flow out of a funnel having a 6 mm opening.

Example 2

0.6 kg of the rough-ground (see Example 1) and subsequently screenedmaterial (coarse fraction through a screen having a mesh size of 300 μm)was rounded in a fluid bed. The apparatus used is a glass tube of 90 mmin diameter and 665 mm in height equipped with a fritted-glass filter G0 as an air diffuser. The quantity added (4% of the proportion smallerthan 80 μm) is swirled by a quantity of air of 22 Nm³/h for 10 minutesand 30 minutes respectively. The material abraded off is discharged by astream of air. 20% and 30% of the material respectively was dischargedas fine material. The dispersibility in cement mortar, at a relativecoloring strength of 95% and 94% respectively, is good. The materialflows well. The dust fraction is very small (dust measurement using theHeubach Dustmeter in accordance with DIN 55 992), the bulk density ishigher than that of the starting material. 100% of the material islarger than 125 μm, as shown by a control screening. The averageparticle size is ca. 600 μm. The quantity separated off as fine materialis 34% and 42% respectively.

Example 3

1 kg of the material, after comminution by the crusher (see Example 1)is placed in a drum screen of 220 mm in diameter, 310 mm in length andhaving a mesh size of 300 μm, operating at 10 revolutions per minute(rev/min), which is contained in a closed housing. Suction is applied atthe top of the housing, which is ca. 35 1 in volume. After a runningtime of 10 minutes and 30 minutes respectively, 30% and 37% respectivelyare removed by suction. The material of irregular shape exhibitsdistinct rounding. Dispersibility and flow properties are good. Thetendency to form dust is low. A further rolling (after-rounding) on arotary disk (40 cm diameter, 42 rev/min, 47° inclination) brings nofurther improvements.

Example 4 (Comparison)

The rough-ground material (see Example 1) is subsequently rolled byafter-rolling for 15 minutes on the rotary disk (40 cm in diameter, 42rev/min, 47° inclination) under suction. The yield is 95%. Thedispersibility is good. The material flows well. The proportion largerthan 80 μm is 100%. However the formation of dust in the dustmeter, atca. 300 mg, is very poor. In comparison, the dust values of the granularmaterials from Example 2 and Example 3 in the dustmeter are ca. 100 mg.

Example 5

250 g of Corasol C30 carbon black (a Degussa trade product) respectively250 g of Monarch 800 carbon black (a Cabot Corp. trade product) and 250g of Bayferrox 330 iron oxide black (a Bayer AG trade product) weremixed for 18 minutes in a mixer with ammonium lignosulphonate and V 100machine oil in different quantities. The mixture was moulded once ortwice using various linear forces in a compactor of type WP50N (from theAlexanderwerk in Remscheid) and then comminuted in an RFG finegranulator (from the Alexanderwerk in Remscheid) using a screen with amesh size of 1.5 mm. The comminuted product was separated into twofractions using a screen with a mesh size of 250 μm. The fraction largerthan 250 μm was tested and displayed good flowability (the correspondingpowder mixture had poor flowability). The remaining data for thefraction and the starting powders are contained in Table 2. The relativecolor intensity was measured in comparison with a corresponding mixtureof the starting powder.

TABLE 1 Dust Discharge Bulk Screen Yield Dispersibility measurement timedensity analysis Sample Comments on sample [%] * [mg] [s] [g/cm³] >80 μmExample 1 pressed and 100 100 — does not 1.07 95 comminuted flow Example2 screened: 10 min. in 66 95 104 32 1.14 100 the fluid bed screened: 30min. in 58 94 85 32 1.17 100 the fluid bed Example 3 10 min. through 7096 95 32 1.10 100 drum screen 30 min. through 63 94 71 30 1.11 100 drumscreen 10 min. through 70 95 96 30 1.11 100 drum screen plus 15 min.rolling on rotary disk Example 4 not screened, 15 min. 95 98 304 29 1.22100 rolling on rotary disk * in cement mortar; rel. color intensity [%]

TABLE 2 Rel. color Linear force Bulk density Yield Outflow timeintensity in Additives [kN/cm] [g/ml] [%] [sec.] concrete [%] Monarch800 carbon black powder — — 0.20 — non-flowable 100 Bayferrox 330:Monarch 800 2% LS + 7 0.6 61 34 83 50:50; granules 1% oil Corasol C 30carbon black powder — — 0.40 — non-flowable 100 Bayferrox: Corasol50:50; granules 8% LS + 5 0.6 54 31 96 1% oil Bayferrox 330 iron oxidepowder — — 0.7 — non-flowable 100 LS - ammonium lignosulfonate oil -machine oil V 100

What is claimed is:
 1. A process of using granular materials produced bya) mixing one or more inorganic pigments with one or more auxiliarysubstances promoting processability, b) subjecting this mixture to apressing or briquetting step to produce a pressed or briquetted product,c) comminuting the pressed or briquetted product to produce a comminutedproduct, d) dividing the comminuted product into two or more fractions,and e) removing a first fraction of particles having at least 85% of theparticles at least 80 μm, which forms a granular product fraction,wherein the process of using comprises mixing the first fraction with atleast one material selected from the group consisting of buildingmaterial and organic media for coloring the at least one materialselected.
 2. A process for coloring building materials comprising thesteps of a) mixing one or more inorganic pigments with one or moreauxiliary substances promoting processability, b) subjecting thismixture to a pressing or briquetting step to produce a pressed orbriquetted product, c) comminuting the pressed or briquetted product toproduce a comminuted product, d) dividing the comminuted product intotwo or more fractions, e) removing a first fraction of particles havingat least 85% of the particles at least 80 μm, which forms a granularproduct fraction, and f) mixing the first fraction of particles with acement-containing building material in a quantity of from 0.1 to 10 wt.%, based on the cement contained in the building material.
 3. Theprocess of claim 2 wherein the mixture of inorganic pigment andauxiliary substance is compacted at low line forces between 0.1 and 50kN/cm.
 4. The process of claim 2 wherein the mixture of inorganicpigment and auxiliary substance is compacted using a compaction forcethat results in compacted inorganic granules which when mixed into thebuilding material impart thereto a color equally good as that ofinorganic pigment powders.
 5. The process of claim 2 wherein theinorganic pigment is selected from the group consisting of iron oxide,titanium dioxide, chromium oxide, rutile mixed phase pigments andmixtures of these pigments with carbon black.
 6. The process of claim 2wherein a sufficient quantity of auxiliary substance is used to providecompacted inorganic granules comprising from 0.001 to 10 wt % auxiliarysubstance.
 7. The process of claim 2 wherein the auxiliary substance islignin sulphonate.
 8. The process of claim 7 wherein a sufficientquantity of auxiliary substance is used to provide compacted inorganicgranules comprising 0.001 to 10 wt % lignin sulphonate.
 9. The processof claim 2 wherein the pressed or briquetted product has a residualwater content of less than 2 wt %.
 10. The process of claim 2 whereinthe particles of the granular product fraction have a size between 100and 1000 μm.
 11. The process of claim 1 wherein the mixture of inorganicpigment and auxiliary substance is compacted at low line forces between0.1 and 50 kN/cm.
 12. The process of claim 1 wherein a sufficientquantity of auxiliary substance is used to provide compacted inorganicgranules comprising from 0.001 to 10 wt % auxiliary substance.
 13. Theprocess of claim 1 wherein the auxiliary substance is lignin sulphonate.14. The process of claim 13 wherein a sufficient quantity of auxiliarysubstance is used to provide compacted inorganic granules comprising0.001 to 10 wt % lignin sulphonate.
 15. A process of using granularmaterials produced by a) mixing one or more inorganic pigments with oneor more auxiliary substances promoting processability, b) subjectingthis mixture to a pressing or briquetting step to produce a pressed orbriquetted product, c) comminuting the pressed or briquetted product toproduce a comminuted product, d) dividing the comminuted product intotwo or more fractions, and e) removing a first fraction of particleshaving at least 85% of the particles at least 80 μm, which forms agranular product fraction, wherein the process of using comprises mixingthe first fraction with a dye or slurry medium so as to produce dispersedyes or slurries.
 16. The process of claim 15 wherein the mixture ofinorganic pigment and auxiliary substance is compacted at low lineforces between 0.1 and 50 kN/cm.
 17. The process of claim 15 wherein asufficient quantity of auxiliary substance is used to provide compactedinorganic granules comprising from 0.001 to 10 wt % auxiliary substance.18. The process of claim 15 wherein the auxiliary substance is ligninsulphonate.
 19. The process of claim 18 wherein a sufficient quantity ofauxiliary substance is used to provide compacted inorganic granulescomprising 0.001 to 10 wt % lignin sulphonate.